Morphology and Rheological Behaviors of Polycarbonate/High Density Polyethylene in situ Microfibrillar Blends

Abstract

Summary: Polycarbonate (PC)/high density polyethylene (HDPE) in situ microfibrillar blends were fabricated by a slit die extrusion, hot stretching, and quenching process. Despite PC and HDPE having a high viscosity ratio, which is usually disadvantageous to fibrillation, the morphological observation indicated that the blends had well‐defined PC microfibrils. The size and amount of the PC fibrils were nonuniform through the thickness of the extrudate, and were also affected by the PC concentration and hot stretch ratio. There were coarse and dense fibrils in the core zone, while these fibrils became finer and reduced in number toward the surface. The melt flow rate (MFR) of the PC/HDPE microfibrillar blend decreased with the increase of PC concentration, but increased with the larger hot stretching rate (or hot stretching ratio, HSR). Besides, it was found that the fibrillar blend had better flowability than the common blend with spherical particles at the same PC concentration. Temperature was also an important factor influencing the MFR due to the temperature dependence of PC and HDPE viscosity, and the PC phase morphology. The PC microfibrils could not be preserved beyond 230 °C and transformed into spherical particles. The rheological behaviors at various shear rates were studied by capillary rheometer. The orientation of PC fibrils and HDPE molecules with higher shear rate led to a decrease in the viscosity of microfibrillar blend. The data obtained in this study can help construct the technical foundation for recycling and utilization of PC and HDPE waste by manufacture of microfibrillar blends in future work.

Double Yielding in Injection‐Molded Polycarbonate/Polyethylene Blends: Composition Dependence

“…Typical anisotropic skin‐core structures were observed for all the blends as in many other injection‐molded blends,33–42 in which the dispersed PC particles exhibit different shapes and sizes in the core, sub‐skin, and intermediate layers. Although the phase viscosity ratio (ratio of viscosity of the dispersed phase to that of the matrix) is more than one,43 amorphous PC particles can deform under strong shear and elongational fields 30. In the core layer, most PC particles remained spherical in shape except a few slightly deformed ones, as shown in Figure 2.…”

Compatible polycarbonate/polyamide 6,6 blends with fibrillar morphology

“…It is known that in immiscible thermoplastic blends, 37 fibril morphologies are more easily produced (provided processing conditions and composition are the same 38 ) when the viscosity ratio (k ¼ g d /g m where g d and g m are respectively, the viscosities of the dispersed phase and of the matrix) of the blends components 39 is below unity (the matrix more viscous than the dispersed phase). Therefore, the viscosity of the blend components was measured by capillary rheometry at a temperature of 270 C and a shear rate of 2000 s…”

Morphology evolution of a liquid crystalline polymer confined by highly packed glass beads in polycarbonate

“…In the case of larger viscosity ratio, good fibrillation of the dispersed phase could be obtained by hot-drawing [13,18,24] or coextrusion method [25]. Consider the present PC/VA/GB composites.…”